1. Field of the Invention
The present invention relates generally to the field of supercharged motorcycles. More specifically, the present invention concerns a supercharger drive for a motorcycle that fluidly communicates with the motorcycle drive train.
2. Discussion of Prior Art
It is known in the art to supercharge an internal combustion engine to provide increased airflow to the engine and thereby enhance the power output of the engine. There are several types of superchargers known in the art, including, for example, Roots-type superchargers and centrifugal superchargers, both of which are driven off of the crankshaft of the engine. One exemplary centrifugal supercharger well advanced in the art and particularly resistant to failure is disclosed in U.S. application patent Ser. No. 10/641,619 entitled CENTRIFUGAL COMPRESSOR WITH IMPROVED LUBRICATION SYSTEM FOR GEAR-TYPE TRANSMISSION, filed Aug. 14, 2003 (the “Jones '619 application”), hereby incorporated by reference herein.
It is also known in the art to supercharge a motorcycle engine, including the distinctive V-twin engine design found on Harley-Davidson® motorcycles. However, motorcycle engines and particularly Harley-Davidson® V-twin motorcycle engines present a number of design considerations. For example, prior art superchargers, particularly superchargers that do not utilize multiple bearing arrangements or a self-contained dedicated lubrication system, can be subject to premature failure, or failure prior to the life expectancy of the motorcycle's engine, particularly where the drive assembly is not maintained within very tight tolerances. Failure of these prior art superchargers can be problematic as it may in turn cause catastrophic engine failure. Prior art superchargers are often interconnected to the motorcycle drive train with geared drives. One of these drives is disclosed in U.S. application patent Ser. No. 10/605,880 entitled SUPERCHARGED MOTORCYCLE, filed Nov. 3, 2003 (the Jones '880 application), hereby incorporated by reference herein. The potential for such engine failure is exacerbated where the supercharger is directly integrated with the engine, such as sharing a common lubrication system, as foreign debris occasioned by supercharger failure can leak into the internal components of the engine.
Additionally, these prior art superchargers and their associated drive assemblies often interfere with the rider's normal operating position. In particular, drive assemblies for superchargers are typically driven off of the engine's crankshaft, however, the crankshaft is typically positioned adjacent the footboard and foot controls of the motorcycle and therefore there is very limited space in and around the crankshaft in which to position drive components. Therefore, in order to place the drive components and/or the supercharger itself in the crowded area around the crankshaft, the components can undesirably alter or interfere with the rider's otherwise normal, comfortable operating position and/or the rider's ability to readily manipulate the foot controls. Additionally, these components in prior art installations may be arranged such that they undesirably affect the balance or reduce the effective bank angle of the motorcycle.
Some of these problems, as well as others, associated with supercharging a V-twin motorcycle engine are exemplified in U.S. Pat. No. 6,105,558 entitled SUPERCHARGING APPARATUS, issued Aug. 22, 2000.
Accordingly, there is a need for an improved drive assembly for use with supercharged motorcycles that does not suffer from these problems and limitations.